This paper presents an experimental study of the heat transfer to both Newtonian and nonNewtonian fluids flowing in a Sulzer SMX static mixer. The extensive experiments were performed under varying operating conditions: the number of mixing elements aligned in series (6 to 18), the fluid flowrate (2.78 x 10(-6) to 8.33 x 10(-5) m(3).s(-1)) and the wall temperature of the static mixer (293 to 363 K). An adequate design correlation gathering well all 445 experimental data points was proposed over a wide range of the Peclet number: 1500 < Pe < 105000. This correlation compares favorably with previous work and extends significantly the investigated range of experimental conditions. Finally, it was shown that the enhancement of heat transfer is achieved by a factor of 5 with respect to an empty tube in the laminar flow regime.